The present invention relates to communication devices and their method of operation and, in particular, to communication devices comprising a first radio, e.g. a long-range radio, and a second radio, e.g. a short-range radio.
Communication devices comprising two radios for operating in, for example, a short-range radio system and a long-range radio system are known in the art. The terminology of long-range radio system and short-range radio system refers to that the maximum power of transmission in a long-range radio system is greater than the maximum power of transmission in the short-range radio system. It should be noted, however, that the actual range in terms of distance could in fact be greater for the short-range radio than for the long-range radio. The long-range radio system may be used by the communication device to communicate with, for example, a base station in a cellular radio system. The short-range radio system may be used by the communication device to communicate with other devices in its surrounding, such as a home base station or an office base station. Another application for the short-range radio system is communication between a mobile phone, such as a cellular phone, and a hands-free equipment, for example, installed in a car.
Normally the short-range radio and the long-range radio of the communication device comprise frequency synthesizers for generating the signals to be transmitted by the respective radios. In most cases the frequency synthesizers operate well when the power supply provides a constant voltage. Even when power is supplied from a battery and the battery voltage changes slowly over time due to the charging status of the battery, the power supply voltage can be considered constant during a burst transmission.
Whilst the known communication device described above functions quite adequately, it does have a number of disadvantages.
A voltage drop at the power supply may be experienced when the long-range radio transmits. The reason for this is that the long-range radio often transmits with a relatively high power level which results in a large supply current from the power supply. The impedance of the power supply distribution lines and, if a battery makes up the power supply, the internal impedance of the battery result in the voltage drop. The output frequency of the frequency synthesizer used in the short-range radio system will change due to this voltage drop. Consequently, if the short-range radio is transmitting when the power supply voltage is dropping or recovering, due to the commencing or discontinuing of transmission by the long-range radio, the signal transmitted by the short-range radio will also change. In such a case a problem arises in that a receiver of another short-range radio device may have difficulties in receiving and decoding the signal transmitted by the short-range radio.
It is an object of the present invention to provide a communication device and a method of operating a communication device which overcome or alleviate the above mentioned problem.
According to an aspect of the present invention there is provided a method of operating a communication device comprising circuitry for non-continuous transmission in a first radio system and circuitry for non-continuous transmission in a second radio system, the method comprising the step of avoiding transmission by the communication device within the second radio system which is planned to occur at the points in time the first radio system will commence or discontinue to transmit.
According to a further aspect of the present invention there is provided a communication device for communication in a first radio system and in a second radio system comprising a first radio transmitter for transmitting a signal to a radio apparatus in the first radio system, first controller means for controlling the operation of the first radio transmitter, a second radio transmitter for transmitting a signal to a radio apparatus in the second radio system, and second controller means for controlling the operation of the second radio transmitter, wherein the second controller means is adapted to avoid transmission by the second radio transmitter which is planned to occur at the points in time the first radio system will commence or discontinue to transmit.
The method of operating a communication device and the communication device achieve the advantage that a signal transmitted by the second radio transmitter, e.g. a short-range radio transmitter, is not affected by the operation of the first radio transmitter, e.g. long-range radio transmitter.
According to a further aspect of the present invention transmission by the communication device within the second radio system which is planned to occur during periods of time the first radio system will transmit is avoided.
The advantage of this is that the second transmitter, e.g. a short-range radio, cannot be affected by the operation of the first transmitter, e.g. a long-range radio, since they never transmit at the same time.
Preferably, transmission is avoided by delaying or advancing transmission within the second radio system.
In a further aspect of the present invention the transmission within the second radio system, e.g. a short-range radio system, takes place as packets, each packet being transmitted within a time-slot of a frame and each frame being made up of a number of time-slots.
According to a further aspect of the present invention each time-slot is partitioned into two pre-defined parts. In the first part the second radio, e.g. a short-range radio, of the dual communication device is allowed to transmit, i.e. another short-range radio is receiving. In the second part the short-range radio of the other short-range radio is allowed to transmit, i.e. the short-range radio of the dual communication device is receiving.
According to a further aspect of the present invention transmission is avoided during at least the whole of the time-slot in which it is decided that transmission is to be avoided.
The advantage of this is that if another radio device, e.g. another short-range radio device, is only allowed to transmit in a time-slot where it has received a transmitted packet from the second radio, e.g. the short-range radio, of the dual radio communication device, the dual radio communication device can control the transmission of this other radio device, i.e. the other short-range radio device, such that it occurs only during periods of time when the dual radio communication device knows that its first radio transmitter, i.e. the long-range radio transmitter, will not commence or discontinue to transmit. Consequently, the second radio receiver, i.e. the short-range radio receiver, of the dual radio communication device does not need to receive a radio signal, i.e. a short-range radio signal, during periods of time when the receiver frequency synthesizer may be disturbed due to a change in the potential of the power supply.
Preferably, the method of operating a communication device further comprises the step of determining if a packet to be delayed, as a result of delaying transmission within the second radio system, includes compressed data covering one slot and if so replacing the packet to be delayed with a packet of the type corresponding to compressed data covering several slots.
Preferably, the communication device further comprises means for determining if a packet to be delayed, as a result of delaying transmission within the second radio system, includes compressed data covering one slot, and means for replacing the packet to be delayed with a packet of the type corresponding to compressed data covering several slots if the packet corresponds to a packet with compressed data covering one slot.
Advantageously, the method of operating a communication device further comprises the step of establishing the number of slots, set equal to n, the packet to be delayed will be delayed, and wherein the packet to be delayed is replaced with a packet of the type corresponding to compressed data covering m slots, where m is equal to n+1.
Advantageously, the communication device further comprises means for establishing the number of slots, set equal to n, the packet to be delayed will be delayed, and wherein the means for replacing the packet to be delayed replaces the packet with a packet of the type corresponding to compressed data covering m slots, where m is equal to n+1.
The advantage with this is that packets with compressed data covering one slot can be delayed although they should have been transmitted every slot.
According to a further aspect of the present invention there is provided a method of operating a communication device comprising circuitry for communication in a radio system in which transmission takes place as bursts, each burst being transmitted within a time-slot of a frame and each frame being made up of a number of time-slots, the method comprising the steps of i) establishing information representing the points in time a time-slot begins and ends, ii) receiving a transmitted radio burst in the radio system, iii) establishing whether the received radio burst is received during said time-slot and iv) allowing returned transmission within the time-slot only if a packet was received during the time-slot.
According to a further aspect of the present invention there is provided a communication device for communication in a radio system in which transmission takes place as bursts, each burst being transmitted within a time-slot of a frame and each frame being made up of a number of time-slots, the device comprising a radio transmitter for transmitting a signal to a radio apparatus in the radio system, controller means for controlling the operation of the radio transmitter, a radio receiver for receiving a transmitted burst from a radio apparatus in the radio system, first means for establishing information representing the points in time a time-slot begins and ends, second means for establishing whether a received radio burst is received during said time-slot and wherein the controller means allows the radio transmitter to transmit during said time-slot only if a radio burst has been received during the time-slot.
The advantage of this method of operating a communication device and this communication device is that transmission can be controlled to occur under control by another radio device. This allows the other radio device to avoid the need for receiving a radio signal when it is unsuitable. This may be during periods of time when the other radio device knows that a separate transmitter will commence or discontinue to transmit and, consequently, may disturb a receiver frequency synthesizer due to a change in the potential of its power supply.
The advantage that a signal transmitted by the second radio, e.g. a short-range radio, is not affected by the operation of the first transmitter, e.g. a long-range transmitter, is achieved by avoiding transmission by the communication device within the second radio system, i.e. the short-range radio system, which is planned to occur at the points in time the first radio system, i.e. the long-range radio system, will commence or discontinue to transmit.
The advantage that packets with compressed data covering one slot can be delayed although they should have been transmitted every slot is achieved by replacing the packet to be delayed with a packet of the type corresponding to compressed data covering several slots if the packet corresponds to a packet with compressed data covering one slot.
The advantage that transmission can be controlled to occur under control by another radio device is achieved by allowing returned transmission within the time-slot only if a packet was received during the time-slot.